Direct current (DC), pulse, or alternating current (AC) ionization systems having high voltage power supplies and an ionizer typically employ one of two methods to control the balance or net charge of the target area. Amplitude control adjusts the relative amplitudes of positive and negative ionization. This can be achieved through adjustment of either the current or the voltage being applied to the ionizer.
Duty cycle control can also be used to control the balance or net charge of the target area. In this type of control, adjustments to the positive and negative ionization cycles are made relative to the time axis. Control is achieved by lengthening or shortening the relative duty cycle of the positive and negative ionization.
For the purposes of neutralization and/or balance, adjustments to pulse frequency and waveform shape may also be employed. High voltage pulse frequency may be adjusted up or down for control. Techniques to optimize the exact shape of the output pulses may also be employed. Adjustments to such parameters are made to optimize performance.
It is desirable to provide a control method that increases the dynamic range of ionizer control relative to the target area, particularly in applications where the ionizer is close to highly charged objects, such as a moving web or other insulators. It is further desirable to enhance the resolution of either control technique.